SUWIND - window traces by key word
suwind stdout [options]
Required Parameters:
none
Optional Parameters:
verbose=0 =1 for verbose
key=tracl Key header word to window on (see segy.h)
min=LONG_MIN min value of key header word to pass
max=LONG_MAX max value of key header word to pass
abs=0 =1 to take absolute value of key header word
j=1 Pass every j-th trace ...
s=0 ... based at s (if ((key - s)%j) == 0)
count=ULONG_MAX ... up to count traces
reject=none Skip traces with specified key values
accept=none Pass traces with specified key values(see notes)
processing, but do no window the data
Options for vertical windowing (time gating):
dt=tr.dt (from header) time sampling interval (sec)
tmin=0.0 min time to pass
tmax=(from header) max time to pass
itmin=0 min time sample to pass
itmax=(from header) max time sample to pass
nt=itmax-itmin+1 number of time samples to pass
Notes:
On large data sets, the count parameter should be set if
possible. Otherwise, every trace in the data set will be
examined. However, the count parameter overrides the accept
parameter, so you can't specify count if you want true
unconditional acceptance.
The accept option is a bit strange--it does NOT mean accept ONLY
the traces on the accept list! It means accept these traces,
even if they would otherwise be rejected (except as noted in the
previous paragraph). To implement accept-only, you can use the
max=0 option (rejecting everything). For example, to accept
only the tracl values 4, 5 and 6:
... | suwind max=0 accept=4,5,6 | ...
Another example is the case of suppressing nonseismic traces in
a seismic data set. By the SEGY standard header field trace id,
trid=1 designates traces as being seismic traces. Other traces,
such as calibration traces may be designated by another value.
Example: trid=1 seismic and trid=0 is nonseismic. To reject
nonseismic traces
... | suwind key=trid reject=0 | ...
On most 32 bit machines, LONG_MIN, LONG_MAX and ULONG_MAX are
about -2E9,+2E9 and 4E9, they are defined in limits.h.
Selecting times beyond the maximum in the data induces
zero padding (up to SU_NFLTS).
The time gating here is to the nearest neighboring sample or
time value. Gating to the exact temporal value requires
resampling if the selected times fall between samples on the
trace. Use suresamp to perform the time gating in this case.
It doesn't really make sense to specify both itmin and tmin,
but specifying itmin takes precedence over specifying tmin.
Similarly, itmax takes precedence over tmax and tmax over nt.
If dt in header is not set, then dt is mandatory
Credits:
SEP: Einar Kjartansson
CWP: Shuki Ronen, Jack Cohen, Chris Liner
Warnemuende: Toralf Foerster
Trace header fields accessed: ns, dt, delrt, keyword
Trace header fields modified: ns, delrt, ntr